C HAPTER 17 Organosulfur Compounds 17.1 INTRODUCTION Sulfur is directly below oxygen in the periodic table. The sulfur atom has six valence electrons, as shown in Figure 17.1, and its electron configuration is {Ne}3 s 2 3 p 4 . Because of their very similar valence shell electron configurations, oxygen and sulfur behave somewhat alike chemically. How- ever, unlike oxygen, the sulfur atom has three underlying 3 d orbitals, and its valence shell can be expanded to more than eight electrons. This makes sulfur’s chemical behavior more diverse than that of oxygen. For example, sulfur has several common oxidation states, including –2, +4, and +6, whereas most chemically combined oxygen is in the –2 oxidation state. 17.1.1 Classes of Organosulfur Compounds The hydride of sulfur is H 2 S (Figure 17.1), a highly toxic gas discussed in Section 11.9. Substitution of alkyl or aryl hydrocarbon groups such as phenyl and methyl (Figure 17.1) for H on hydrogen sulfide leads to a number of different organosulfur compounds. These include thiols (R–SH) and thioethers (R–S–R). Because of the availability of 3 d orbitals, sulfur that is bonded to hydrocarbon moieties can also be bonded to oxygen, adding to the variety of organosulfur com- pounds that can exist. Despite the high toxicity of H 2 S, not all organosulfur compounds are particularly toxic. Many of the compounds have strong, offensive odors that warn of their presence, which reduces their hazard. 17.1.2 Reactions of Organic Sulfur Organic sulfur undergoes a number of toxicological chemical reactions. These include the following: • Oxidation of sulfur • Reduction of sulfur • Removal of sulfur from a molecule • Addition of sulfur-containing groups Examples of these kinds of reactions, some of which are very important in xenobiotic metab- olism, are given below. Oxidation of sulfur is called S-oxidation . Thiols can be oxidized to form disulfides: 2R–SH + {O} → R–S S–R + H 2 O (17.1.1) L1618Ch17Frame Page 347 Tuesday, August 13, 2002 5:40 PM Copyright © 2003 by CRC Press LLC The same kind of reaction occurs with aminothiols, such as in the oxidation of cysteamine, H 2 NCH 2 CHSH, to cystamine, H 2 NCH 2 CH 2 S SCH 2 CH 2 NH 2 . S-oxidation may also involve sulfur in organosulfide compounds: (17.1.2) and sulfur on thioamides: (17.1.3) An example of sulfur reduction is disulfide reduction , as shown by the following reaction: (17.1.4) This reaction converts disulfiram, a therapeutic agent for the treatment of alcohol abuse, discussed in Section 17.3, to dithiocarb (diethylthiocarbamate), a substance that strongly binds metals and is used for the treatment of nickel carbonyl poisoning. Desulfuration is the term given to removal of sulfur from a molecule. One of the most common desulfuration reactions occurs with sulfur bonded to phosphorus. A common desulfuration reaction is the enzyme-mediated conversion of parathion to paraoxon (see discussion of organophosphate insecticides in Section 18.7): (17.1.5) Figure 17.1 Sulfur atom, compounds, and substituent groups. C H H H SCS : . . S :: H H S Lewis symbol of sulfur atom Lewis structure of hydrogen sulfide Carbon disulfide Phenyl group Methyl group Sulfoxidation {O} SRR' S O RR' RC S N H H RC S N O H H S-oxidation Enzymatic reduction 2 Disulfiram Dithiocarb S SCCNN C 2 H 5 C 2 H 5 H 5 C 2 H 5 C 2 SS HS C N C 2 H 5 C 2 H 5 S {O}, enzymatic oxidation Parathion Paraoxon OP O C 2 H 5 NO 2 H 5 C 2 O O O C 2 H 5 S H 5 C 2 PNO 2 OO L1618Ch17Frame Page 348 Tuesday, August 13, 2002 5:40 PM Copyright © 2003 by CRC Press LLC The most significant instance of addition of a sulfur-containing group is the phase II conjugation to sulfate of a xenobiotic compound or its phase I metabolite (see Section 7.4.3) by the action of adenosine 3'-phosphate-5'-phosphosulfate, a sulfotransferase enzyme that acts as a sulfating agent: (17.1.6) 17.2 THIOLS, SULFIDES, AND DISULFIDES Substitution of alkyl and aryl groups for H on H 2 S yields thiols and sulfides (thioethers). Structural formulas of examples of these compounds are shown in Figure 17.2. 17.2.1 Thiols Thiols are also known as mercaptans. The lighter alkyl thiols, such as methanethiol, are fairly common air pollutants with odors that may be described as ultragarlic. Inhalation of even very low concentrations of the alkyl thiols in air can be very nauseating and result in headaches. Exposure Figure 17.2 Common low-molecular-mass thiols and sulfides. All are liquids at room temperature, except for methanethiol, which boils at 5.9°C. HC SH H H H H H HCCCSH H H H HCC SH H H H H H H H CCCSH H H C HH H H H CCCSH H H H H CSH H H SH SH SCC H H H H H H S S CCC H H H H H CH H H H S H Methanethiol Ethanethiol 1-Propanethiol 2-Propene-1-thiol 1-Butanethiol 2-Butanethiol 1-Pentanethiol Alpha-toluenethiol Cyclohexanethiol HC H H CC H H H H SH 3 HC H H CC H H H H SH 8 1-Decanethiol Benzenethiol Dimethyl sulfide Thiophene (an unsaturated cyclic sulfide) Thiophane HC H H SC H H Methylbenzyl sulfide OH O - H + S O O + Phenol Phase II sulfate conjugate SOH O O (Sulfating agent) L1618Ch17Frame Page 349 Tuesday, August 13, 2002 5:40 PM Copyright © 2003 by CRC Press LLC to higher levels can cause increased pulse rate, cold hands and feet, and cyanosis. With extreme cases, unconsciousness, coma, and death may occur. The biochemical action of alkyl thiols likely is similar to that of H 2 S, and they are precursors to cytochrome oxidase poisons. Volatile methanethiol from biogenic sources is released to the atmosphere in coastal and ocean upwelling areas. 1 Methanethiol and volatile liquid ethanethiol (bp, 35°C) are intermediates in pesticide synthesis and odorants placed in lines and tanks containing natural gas, propane, and butane to warn of leaks. Information about their toxicities to humans is lacking, although these compounds and 1-propanethiol should be considered dangerously toxic, especially by inhalation. Also known as amyl mercaptan, 1-pentanethiol (bp, 124°C) is an allergen and weak sensitizer that causes contact dermatitis. Anaerobic bacteria in the colon produce significant quantities of methanethiol along with hydrogen sulfide. Rodent studies indicate that these substances are detoxified to thiosulfate by the action of a specialized detoxification system that operates in the mucous layer of the colon lining. 2 The failure of this system may contribute to some diseases of the colon, such as ulcerative colitis. A typical alkenyl mercaptan is 2-propene-1-thiol, also known as allyl mercaptan. It is a volatile liquid (bp, 68°C) with a strong garlic odor. It has a high toxicity and is strongly irritating to mucous membranes when inhaled or ingested. Alpha-toluenethiol, also called benzyl mercaptan (bp, 195°C) is very toxic orally. It is an experimental carcinogen. The simplest of the aryl thiols is benzenethiol, phenyl mercaptan (bp, 168°C). It has a severely repulsive odor. Inhalation causes headache and dizziness, and skin exposure results in severe contact dermatitis. 17.2.2 Thiols as Antidotes for Heavy Metal Poisoning Toxic heavy metals, such as cadmium, lead, and mercury, are sulfur seekers that bind strongly with thiol groups, which is one of the ways in which they interact adversely with biomolecules, including some enzymes. Advantage has been taken of this tendency to use thiols in chelation therapy in heavy metal poisoning. Among the thiols tested for this purpose are meso -2,3-dimer- captosuccinic acid, diethyldimercapto succinate, α -mercapto- β -(2-furyl), and α -mercapto- β -(2- thienyl) acrylic acid. 3 The structural formulas for the first two are 17.2.3 Sulfides and Disulfides Dimethylsulfide is an alkyl sulfide or thioether. It is a volatile liquid (bp, 38°C) that is moderately toxic by ingestion. Thiophene is the most common cyclic sulfide. It is a heat-stable liquid (bp, 84°C) with a solvent action much like that of benzene. It is used in the manufacture of pharma- ceuticals and dyes, as well as resins that also contain phenol or formaldehyde. Its saturated analog is tetrahydrothiophene, or thiophane. Ruminant animals produce dimethylsulfide, a fraction of which is exhaled. 4 Therefore, cows’ breath is a source of this compound in terrestrial atmospheres. Dimethylsulfide is produced in enormous quantities by marine organisms. This volatile compound is the largest source of biogenic sulfur in the atmosphere and is responsible for some of the odor emanating from coastal mud flats. C C SH SH O OH O HO meso -2,3-Dimercaptosuccinic acid C O C H SH C H SH CO O O H H C H H CH CCH HH HH Diethyldimercapto succinate L1618Ch17Frame Page 350 Tuesday, August 13, 2002 5:40 PM Copyright © 2003 by CRC Press LLC It, along with methylbenzyl sulfide and one or two other sulfides, is responsible for the nauseating stench of Halichondria panicea , a marine sponge. The organic disulfides contain the –SS– functional group, as shown in the following two examples: These compounds may act as allergens that produce dermatitis in contact with skin. Not much information is available regarding their toxicities to humans, although animal studies suggest several toxic effects, including hemolytic anemia. 17.2.4 Organosulfur Compounds in Skunk Spray Skunks are small animals that wage powerful defensive warfare in the form of spray that has a sickening offensive odor. The compounds that are responsible for skunk spray odor are organo- sulfur compounds. Although seven or more such compounds have been isolated from the spray of the striped skunk, Mephitis mephitis , it is now believed that there are only three major ones: trans - 2-butene-1-thiol, trans -2-butenyl-1-thioacetate, and 3-methyl-1-butanethiol 5 : 17.2.5 Carbon Disulfide and Carbon Oxysulfide Carbon disulfide (CS 2 ) is one of the most significant sulfur compounds because of its wide- spread use and toxicity. This compound has two sulfur atoms, each separately bonded to a carbon atom. This compound is a volatile, colorless liquid (mp, –111°C; bp, 46°C). Unlike most organo- sulfur compounds, it is virtually free of odor. Although its uses are declining, it has numerous applications in chemical synthesis, as a solvent to break down cellulose in viscose rayon manufac- ture, and in the manufacture of cellophane. It has also been used as an insecticide and fumigant. Acute doses of carbon disulfide inhaled at 100 to l000 ppm irritate mucous membranes and affect the central nervous system, usually causing excitation as a first noticeable effect, followed by restlessness, depression, and stupor. Carbon disulfide intoxication causes reduced conduction velocity in the peripheral nerves, which can be detected by psychomotor tests that exhibit impaired performance. 6 It is a much stronger anesthetic than chloroform (Section 16.2), causing unconscious- ness and even death in cases of high exposure. Symptoms experienced during recovery from severe acute carbon disulfide poisoning resemble those that occur following intoxication from ingestion of ethanol in alcoholic beverages. HCCCCSSCCCCH HHHH HHHH HHHH HHHH SS n-Butyldisulfide Diphenyldisulfide Trans -2-butene-1-thiol C H H H H H CC HS H H C C H H H H H CC S H H CC O C H H H Trans -2-butenyl-1- thioacetate 3-Methyl-1-butane- thiol HS C H H C H H CC HH H H CH 3 L1618Ch17Frame Page 351 Tuesday, August 13, 2002 5:40 PM Copyright © 2003 by CRC Press LLC Chronic carbon disulfide poisoning by absorption through the skin or respiratory tract involves the central and peripheral nervous systems and may cause anemia. Symptoms include indistinct vision, neuritis, and a bizarre sensation of “crawling” on the skin. Psychopathological symptoms may be varied and severe, including excitation, depression, irritability, and general loss of mental capabilities to the point of insanity. Parkinsonian paralysis may result from chronic carbon disulfide poisoning. Carbon disulfide is metabolized by conjugating with the amino acid cysteine to form adducts that rearrange to produce 2-thiothiazolidine-4-carboxylic acid (TTCA): (17.2.1) TTCA is commonly determined by chemical analysis of urine as a biomarker of exposure to carbon disulfide. Another metabolite of carbon disulfide that appears at levels of about 30% those of TTCA in workers exposed to carbon disulfide is 2-thioxothiazolidin-4-ylcarbonylglycine 7 : Replacement of one of the S atoms on carbon disulfide with an O atom yields carbon oxysulfide (COS), a volatile liquid boiling at 50°C. It can decompose to liberate toxic hydrogen sulfide. Carbon oxysulfide vapor is a toxic irritant. At high concentrations this compound has a strong narcotic effect. 17.3 ORGANOSULFUR COMPOUNDS CONTAINING NITROGEN OR PHOSPHORUS Several important classes of organosulfur compounds contain nitrogen or phosphorus. These compounds are discussed in this section. 17.3.1 Thiourea Compounds Thiourea is the sulfur analog of urea. Substitution of hydrocarbon moieties on the N atoms yields various organic derivatives of thiourea, as illustrated in Figure 17.3. Thiourea has been used as a rodenticide. It has a moderate to high toxicity to humans, affecting bone marrow and causing anemia. It has been shown to cause liver and thyroid cancers in experimental animals. Phenylthiourea is likewise a rodenticide. Its toxicity is highly selective to rodents relative to humans, although it probably is very toxic to some other animals. The compound is metabolized extensively, and some of the sulfur is excreted as sulfate in urine. Commonly called ANTU, 1-naphthylthiourea is a virtually tasteless rodenticide that has a very high rodent:human toxicity ratio. The lethal dose to monkeys is about 4000 mg/kg. One SCS HS C H H CCOH O H N HH Cysteine SNH CO 2 H S TTCA 2-thioxothiazolidin-4-ylcarbonylglycine SNH S CN O H C H H COH O L1618Ch17Frame Page 352 Tuesday, August 13, 2002 5:40 PM Copyright © 2003 by CRC Press LLC suicidal adult male human ingested about 80 g of 30% ANTU rat poison, along with a considerable amount of alcohol. He vomited soon after ingestion and survived without significant ill effects. 8 Dogs, however, are quite susceptible to ANTU poisoning. 17.3.2 Thiocyanates Organic thiocyanates are derivatives of thiocyanic acid (HSCN), in which the H is replaced by hydrocarbon moieties, such as the methyl group. Dating from the 1930s and regarded as the first synthetic organic insecticides, these compounds kill insects on contact. Because of their volatilities, the lower-molecular-mass methyl, ethyl, and isopropyl thiocyanates are effective fumi- gants for insect control. Insecticidal lauryl thiocyanate (below) is not volatile and is used in sprays in petroleum-based solvents and in dusting powders. The toxicities of the thiocyanates vary widely by compound and route of administration. Some metabolic processes liberate HCN from thiocyanates. As discussed in Section 11.2.1, HCN is highly toxic, so its generation in the body can result in death. Therefore, methyl, ethyl, and isopropyl thiocyanates should be regarded as rapid-acting, potent poisons. The isothiocyanate group is illustrated in the structure below: Other compounds in this class include ethyl, allyl, and phenyl isothiocyanates. Methylisothiocyan- ate, also known as methyl mustard oil, and its ethyl analog have been developed as military poisons. Both are powerful irritants to eyes, skin, and the respiratory tract. When decomposed by heat, these compounds emit sulfur oxides and hydrogen cyanide. Methylisothiocyanate occurs in the environ- ment from some kinds of vegetables, as a breakdown product of some carbamate insecticides, and from deliberate addition to soil for fumigation. 9 It is a degradation product of the fungicide Vapam: Figure 17.3 Structural formulas of urea, thiourea, and organic derivatives of thiourea. *At least one R group is an alkyl, alkenyl, or aryl substituent. Urea Thiourea Organic derivatives of thiourea* 1-Naphthylthiourea (ANTU)Phenylthiourea NCN H H H H O H NCN H H H S R NCN R R R S NCN H H H S NCN H H H S H H CCCCCCCCCCCCSC HHHHHHHHHHHH HHHHHHHHHHH N Lauryl thiocyanate CN H H H CS Methylisothiocyanate L1618Ch17Frame Page 353 Tuesday, August 13, 2002 5:40 PM Copyright © 2003 by CRC Press LLC 17.3.3 Disulfiram Disulfiram , is a sulfur- and nitrogen-containing compound with several industrial uses, includ- ing applications as a rubber accelerator and vulcanizer, fungicide, and seed disinfectant. It is most commonly known as antabuse, a therapeutic agent for the treatment of alcohol abuse that causes nausea, vomiting, and other adverse effects when ethanol is ingested. Disulfiram is an inhibitor of aldehyde dehydrogenase so that it allows for buildup of the acetaldehyde metabolite of ethanol, causing unpleasant effects that are a deterrent to the ingestion of alcohol. Because of the buildup of acetaldehyde, disulfiram should be given with extreme caution, especially to individuals suffering from liver cirrhosis. 17.3.4 Cyclic Sulfur and Nitrogen Organic Compounds The structural formulas of several cyclic compounds containing both nitrogen and sulfur are shown in Figure 17.4. Basic to the structures of these compounds is the simple ring structure of thiazole . It is a colorless liquid (bp, 117°C). One of its major uses has been for the manufacture of sulfathiazole, one of the oldest of the sulfonamide class of antibacterial drugs. The use of sulfathiazole is now confined to the practice of veterinary medicine because of its serious side effects. Several derivatives of thiazole have commercial uses. One of these is 2-aminothiazole , which has shown a high toxicity to experimental animals. Benzothiazole is another related compound used in organic synthesis. Thiazoles are used as rubber vulcanization accelerators. Benzothiazole, Figure 17.4 Cyclic compounds containing nitrogen and sulfur. HS C S NCH H H H Vapam C H H C H H C H H C H H HC H H C H H HC H H C H H SS NCSSCN Disulfiram (antabuse) N S N SSH N S N N N S H N SNH 2 Thiazole Benzothiazole 2-Aminothiazole 2-Mercaptobenzothiazole Thiabendazole N S SCSCN H H 2-(Thiocyanomethylthio)- benzothiazole (fungicide) N S SCH 3 2-(Methylthio)benzo- thiazole L1618Ch17Frame Page 354 Tuesday, August 13, 2002 5:40 PM Copyright © 2003 by CRC Press LLC 2-mercaptobenzothiazole, and 2-(methylthio)benzothiazole are breakdown products of fungicidal 2-(thiocyanomethylthio)benzothiazole and are common constituents of tannery wastewaters. The human toxicity of 2-(thiocyanomethylthio)benzothiazole is not known, although it has a high toxicity to mice. Thiabendazole , 2-(4'-thiazoyl)benzimidazole, is a systemic fungicide that can be carried through a plant and onto plant leaves. Rats and dogs tolerate a relatively high dose of this chemical, although it tends to make the latter vomit. Acting as an adjuvant (a substance added to a drug or insecticide to give it a desired form and enhance its action and effectiveness), 2- mercaptobenzothiazole is mixed with dithiocarbamate fungicides (see below) to increase their potency. It is an allergen that causes type IV (cell-mediated) hypersensitivity. This condition is manifested by contact dermatitis and a delayed hypersensitive reaction that follows a latent period after exposure. This cell-mediated process results from the sensitization of T lymphocytes. 17.3.5 Dithiocarbamates Dithiocarbamate fungicides consist of metal salts of dimethylthiocarbamate and ethylenebis- dithiocarbamate anions, as shown in Figure 17.5. These fungicides are named in accordance with the metal ion present. For example, the manganese salt of dimethyldithiocarbamate is called maneb, and the zinc and sodium salts are zineb and nabam, respectively. The iron salt of ethylenebisdithio- carbamate is called ferbam, and the zinc salt of this ion is called ziram. These salts are chelates (Section 2.3) in which two S atoms from the ethylenebisdithiocarbamate anion are bonded to the same metal ion in a ring structure. The dithiocarbamate fungicides have been popular for agricultural use because of their effec- tiveness and relatively low toxicities to animals. However, there is concern over their environmental breakdown products, particularly ethylenethiourea (2-imidazolidine thione; see Figure 17.5), which is toxic to the thyroid and has been shown to be mutagenic, carcinogenic, and teratogenic in experimental animals. 17.3.6 Phosphine Sulfides A number of toxicologically important organic compounds have sulfur bound to phosphorus. The simplest of these are the phosphine sulfides, containing only carbon, hydrogen, phosphorus, and sulfur, as illustrated by the example below: Phosphine sulfides tend to be toxic. When burned, they give off dangerous phosphorus oxide and sulfur oxide fumes. Figure 17.5 Dithiocarbamate anions and ethylenethiourea. - SCN CH 3 CH 3 S - SCN SH CCNCS - SHH HH N CC N C S HH HH HH Dimethyldithiocar- bamate anion Ethylenebisdithio- carbamate anion Ethylenethiourea PC 4 H 9 C 4 H 9 S C 4 H 9 Tributylphosphine sulfide L1618Ch17Frame Page 355 Tuesday, August 13, 2002 5:40 PM Copyright © 2003 by CRC Press LLC 17.3.7 Phosphorothionate and Phosphorodithioate Esters The most toxicologically significant organic compounds that contain both phosphorus and sulfur are the thiophosphate esters, which are used as insecticidal acetylcholinesterase inhibitors. The general formulas of insecticidal phosphorothionate and phosphorodithioate esters are shown in Figure 17.6, where R is usually a methyl (–CH 3 ) or ethyl (–C 2 H 5 ) group, and Ar is a moiety of more complex structure, frequently aromatic. Phosphorothionate and phosphorodithioate esters contain the P=S (thiono) group, which increases their insect:mammal toxicity ratios and decreases their tendency to undergo nonenzymatic hydrolysis, compared to their analogous compounds that contain the P=O functional group. The metabolic oxidative desulfuration conversion of P=S to P=O in organisms (see Section 17.1) converts the phosphorothionate and phosphorodithioate esters to species that have insecticidal activity. 17.4 SULFOXIDES AND SULFONES Numerous important organic compounds contain oxygen bonded to sulfur. Among these com- pounds are the sulfoxides and sulfones, shown by the examples in Figure 17.7. Figure 17.6 General formulas and specific examples of phosphorothionate and phosphorodithioate organo- phosphate insecticides. Figure 17.7 Sulfoxides and sulfones. OORP S O R Ar C 2 H 5 C 2 H 5 O O OPNO 2 Cl S O S PONO 2 C 2 H 5 S C 2 H 5 O R S PRO ArS C 2 H 5 CC 2 H 5 CH 3 CCH HOP H SC O S O CH 3 O O C 2 H 5 OSP CCC 2 H 5 S O C 2 H 5 HH HH General formula of phosphorothionate insecticides Parathion General formula of phosphorodithioate insecticides Chlorothion Malathion Disulfoton HC SCH OHH HH S OO HC SCH O O H H H H Dimethylsulfoxide Dimethylsulfone Sulfolane (DMSO) L1618Ch17Frame Page 356 Tuesday, August 13, 2002 5:40 PM Copyright © 2003 by CRC Press LLC [...]... Some examples of such compounds are shown in Figure 17. 10 and discussed briefly here 17. 7.1 Sulfur Mustards The first three compounds shown in Figure 17. 10 are sulfur mustards, which are highly toxic military poisons, or poison gases These are mustard oil (bis(2-chloroethyl)sulfide), sesquimustard (1,2-bis(2-chloroethylthio)ethane), and O-mustard (bis(2-chloroethylthioethyl)ether) The toxic properties of... toluene, and xylene from aliphatic hydrocarbons It is also the solvent in the Sulfinol process by which thiols (Section 17. 2) and acidic compounds are removed from natural gas Sulfolane is used as a solvent for polymerization reactions and as a polymer plasticizer Exposure to sulfolane can cause eye and skin irritation, although its overall toxicity is relatively low 17. 5 SULFONIC ACIDS, SALTS, AND ESTERS... Figure 17. 9 H O H H C O S O C H H O H Dimethylsulfate Sulfuric acid and organosulfate esters One of the major advantages of methanesulfonic acid over sulfuric acid is that it is not an oxidizing species Benzenesulfonic acid and p-toluenesulfonic acid are strong irritants to skin, eyes, and mucous membranes Solutions of sulfonic acids are strongly acidic, and precautions appropriate to the handling... acute toxic effects of DMSO are inhibition of acetylcholinesterase and breakdown of red blood cells (hemolysis) Some DMSO is excreted directly in the urine, and it also undergoes partial metabolism to dimethylsulfide and dimethylsulfone (Figures 17. 2 and 17. 7, respectively) Although dimethylsulfone has some commercial uses, sulfolane (Figure 17. 7) is the most widely used sulfone It is a polar aprotic (no...L1618Ch17Frame Page 357 Tuesday, August 13, 2002 5:40 PM H H H H O H C C C C S OH H H H H O Butanesulfonic acid O S OH O Benzenesulfonic acid H H H H H H H H H H H C C C C C C C C C C H H H H H H H H H H O + S O Na O Sodium 1-( p-sulfophenyl)decane Figure 17. 8 Sulfonic acids and a sulfonate salt Dimethylsulfoxide (DMSO) is a liquid with numerous uses and some very interesting properties... period, conjunctivitis and inflammation of nasal tissue and respiratory tract mucous membranes develop Heavier exposures damage the liver and kidney and cause pulmonary edema and cloudiness of the cornea Death can follow in 3 or 4 days The related compound, diethylsulfate, is an oily liquid It reacts with water to yield sulfuric acid Like dimethylsulfate, it is a strong irritant to tissue and has proven to... salts, such as sodium 1-( p-sulfophenyl)decane, a biodegradable detergent surfactant Its structural formula and those of two sulfonic acids are shown in Figure 17. 8 In general, the sulfonic acids are water soluble and are strong acids because of virtually complete loss of ionizable H+ in aqueous solution They have some important commercial applications, such as in the hydrolysis of fats and oils (see Section... The compound is an experimental mutagen and primary carcinogen 17. 7.2 Sulfur in Pesticides In Section 17. 3, rodenticidal thioureas, insecticidal thiocyanates, and fungicidal dithiocarbamates were discussed Sulfur is a common constituent of other classes of insecticides These prominently include the organophosphate insecticides discussed in Chapter 18 Mobam (Figure 17. 10) is a contact insecticide of the... Section 3.5) to fatty acids and glycerol Benzenesulfonic acid is fused with NaOH in the preparation of phenol Dyes and some pharmaceutical compounds are manufactured from p-toluenesulfonic acid Methanesulfonic acid has been developed as an esterification catalyst in place of sulfuric acid for the synthesis of resins in paints and coatings Copyright © 2003 by CRC Press LLC L1618Ch17Frame Page 358 Tuesday,... C H Methylmethane sulfonate H O H Toxicologically, it has been classified as a primary or direct-acting carcinogen that does not require metabolic conversion to act as a carcinogen.10 Both it and ethyl methane sulfonate are strong biological alkylating agents, although they are regarded as only weak carcinogens 17. 6 ORGANIC ESTERS OF SULFURIC ACID As shown in Figure 17. 9, esters of sulfuric acid exist . are only three major ones: trans - 2-butene-1-thiol, trans -2 -butenyl-1-thioacetate, and 3-methyl-1-butanethiol 5 : 17. 2.5 Carbon Disulfide and Carbon Oxysulfide Carbon disulfide . beverages. HCCCCSSCCCCH HHHH HHHH HHHH HHHH SS n-Butyldisulfide Diphenyldisulfide Trans -2 -butene-1-thiol C H H H H H CC HS H H C C H H H H H CC S H H CC O C H H H Trans -2 -butenyl- 1- thioacetate 3-Methyl-1-butane- thiol HS C H H C H H CC HH H H CH 3 . for this purpose are meso -2 ,3-dimer- captosuccinic acid, diethyldimercapto succinate, α -mercapto- β -( 2-furyl), and α -mercapto- β -( 2- thienyl) acrylic acid. 3